Brush holder assembly for electrical machines



Nov. 15, 1955 E. F. HARTER 2,724,066

BRUSH HOLDER ASSEMBLY FOR ELECTRICAL MACHINES Filed Aug. 2, 1952 5 /ZZ /54 764 /5 /34 f2@ 5 5, l :j E WF1 ma M /6 f? fz /0 ///A 5 /5 54 Z7 '66 INVENTOR ,Z011 I im #4f/*5R United States Patent() BRUSH HOLDER ASSEMBLY FOR ELECTRICAL MACHINES Earl F. Harter, Burlington, Iowa, assignor'to Miehle Printing Press & Manufacturing Co., Chicago, Ill., a corporation of Delaware Application August 2, 1952, Serial No. 302,383

` 7 Claims. (Cl. S10-239) This invention relates to brush holder assemblies for electrical machines, such as generators, motors, and the like. It has for its principal objects the provision of an improved electric-brush holder assembly which is more simple and compact in construction vthan prior assemblies of this type, and which may be readily adjusted to accommodate wear and replacement of the brush.

One feature of the present invention resides in a novel manner of mounting the brush holder on the electrical machine, whereby the mount serves not only to support the holder for the aforesaidfadjustmentbut ialso as an attachment forV shunt and vcross-connections from the brush. According to this feature of the invention, the mount comprises a stud secured to part of the machine and having a flat-sided portion. A releasable device on the stud secures a brush holder bracket in a selected position on a fiat side of the stud, this device being preferably a screw extending through a slot in the bracket and threaded into the flat side of the stud. The brush is slidable in a holder supported bythe bracket and `has a flexible shunt connection leading to a screw or other connecting member mounted on the stud, preferably on another flat side thereof. The cross-connection from the brush is attached tothe stud, as by means of another screw or connecting element mounted on a flat side of the stud. Thus, the current can ow directly from the brush shunt through the stud to the cross-connection, so that the brush holder itself does not carry any current. The brush holder can be easily adjusted by releasing the screw or other device securing the bracket to the ilat side of the mounting stud.

Another feature of the invention resides in a novel construction of the brush holder carried by the adjustable bracket. According to this feature of the invention, the holder includes a plate having a flange secured to the bracket, and a second plate secured to the tirst plate generally parallel to the ange and spaced therefrom a distance approximating the thickness of the brush. The plates and flange form the lateral sides of a receptacle in which the brush is slidable, the brush extending through one end of the receptacle for contact with the commutator ring or other rotating part of the machine. A projection on the rst plate extends generally parallel to the second plate and carries a spring having a part engaging the brush to urge it against the rotating part. Preferably, the second plate has a slot in which the part of the spring extending to the brush is guided. The holder will accommodate a brush of any desired thickness, depending upon the spacing of the second plate from the flange of the rst plate.

For a better understanding of the invention, reference may be had to the accompanying drawing, in which Fig. l is a side view of a preferred form of the new brush-holder assembly;

Fig. 2 is an end view of the assembly shown in Fig. l, and

Fig. 3 is a plan view of the assembly shown in Figs. l and 2.

Referring to the drawings, the commutator ring A or other rotating part of the electrical machine is engaged by a brush 10 which is retained in a brush holder shown generally at 11. The brush holder comprises a plate 12 having a flange 12a extending approximately at right angles to the plane of the plate. A second plate 13 extends in parallel spaced relation to the flange 12a and has a ange 13a extending toward the first flange and parallel to the plate 12. The plate 13 is connected to the plate 12 by a ange 13b, which is spot-welded or otherwise secured to the plate 12. The plates 12 and 13 and their respective flanges 12a and 13a form lateral walls of a receptacle in which the brush 10 is slidable.

A pin 15 is secured at one end to the plate 12 and extends parallel to the plate 13. At its free end portion, the pin 1S has a longitudinal slot 15a for receiving and holding one end of a spring 16 coiled around the pin. The free end portion 16a of the spring extends parallel to the plate 12 and engages the top of the brush 10 to urge the brush through the open bottom of its receptacle and into engagement with the commutator ring A. A vertical slot 13e in the plate 13 receives the projecting portion 16a of the spring and guides it incident to the sliding movement of the brush in its receptacle.

It will be apparent that the spacing between the plate 13 and the ange 12a corresponds approximately to the thickness of the brush 10. ln assembling the parts of the holder, this spacing is selected to accommodate the desired thickness of the brush. Thus, identical parts of the holder may be used for brushes of different thicknesses by simply varying the spacing between the plate 13 and ange 12a.

The ange 12a is welded or otherwise secured to a brush holder bracket 18. As best shown in Fig. 1, the bracket 18 has an inclined portion 18a extending approximately at right angles to the beveled end of the brush which engages the commutator ring A, The inclined portion 18a of the bracket has two spaced slots 18b extending generally in the direction of the brush 10. A releasable device in the form of a screw 19 projects through each of the slots 18b and is threaded into a mounting stud 20 located between the inclined bracket portion 18a and the brush holder 11. This stud is atsided, it being shown as having a square cross-section (Fig. l); and the screws 19 are threaded into one of its iiat sides. A spacer plate 21 is interposed between this flat side and the inclined portion 18a of the bracket, and a flat washer 19a and a lock washer 191; are interposed between the head of each screw and the bracket part 18a. The stud 20 projects from an insulating block 22 to which it is secured. A threaded shank 22a on the insulating block is adapted to be screwed into a stationary part (not shown) of the electrical machine, to support the brush holder assembly.

The ends of a brush shunt 23, which is a flexible insulated wire, are connected to the top of the brush 10 in the brush holder 11. Intermediate its ends, the shunt connection 23is connected to another at side of the stud 20, as by means of a copper fitting 24 secured to the stud by a screw 2S. At its free end portion, the stud 20 has a transverse hole 20a for receiving a cross connection 26, which is clamped in the hole by a screw 27 threaded in one of the flat sides of the stud. The cross connection 26 serves to supply electrical current to or from the brush, as will be readily understood.

In the operation of the brush holder assembly, the brush 10 is urged against the commutator ring A by the coiled spring 16, the brush shunt connection 23 providing a direct path for the current between the brush and the mounting stud 20, the current passing between the cross and shunt 0 connections 26 and 23 by way of the stud itself. Accordingly, the brush holder 11 does not carry any of the current. When it is desired to adjust the brush holder 11 for accurate positioning, or to readjust it after the commutator has been re-faced, the screws 19 are loosened on the stud 20 and the bracket 1S is moved relative to the stud, after which the screws 19 are tightened to hold the bracket and brush holder in the newly adjusted position. Due to the inclination of the bracket part 18a, this adjustment of the bracket on the Hat side of the stud serves to move the beveled end of the brush approximately radially with respect to the commutator ring A to which it is to be engaged.

I claim:

1. A brush holder assembly for electrical machines having a commutator, which comprises a stud adapted to be secured to a part of the machine, the stud having a atsided exterior portion, a brush holder bracket slidable relative to the stud toward and away from the commutator, a releasable device on the stud for securing the bracket on a at exterior side of the stud at selected distances from the commutator, a brush holder supported by the bracket, a brush in the holder, a exible shunt connection between the brush and the stud, and a connecting member located on a second iiat exterior side of the stud and to which the shunt connection is made, whereby the studconnected end of said connection is held stationary during said sliding of the bracket relative to the stud.

2. A brush holder assembly according to claim 1, in which the bracket has a slot, said releasable device being a screw extending through the slot and threaded into the stud.

3. A brush holder assembly according to claim 1, comprising also an element on a at exterior side of the stud for establishing a cross-connection therefrom.

4. A brush holder assembly for electrical machines, which comprises a brush holder bracket, a plate having a ange secured to the bracket, said flange being generally perpendicular to the main body of the plate, a second plate secured to the first plate generally parallel to the flange and spaced therefrom a distance approximating the thickness of the brush hereinafter specified, the second plate having a tiange generally perpendicular to the first flange and parallel to the tirst plate, said plates and flanges forming the lateral walls of a receptacle, a brush slidable in the receptacle and extending through one end thereof, a projection on the first plate extending generally parallel to the second plate, and a spring mounted on the projection and having a part engaging the brush to urge the same in the direction of said end of the receptacle.

5. A brush holder assembly according to claim 4, in which the second plate has a slot extending in the direction in which the brush is slidable in the receptacle, said spring part extending through the plate slot and being guided therein.

6. A brush holder assembly according to claim 4, comprising also a stud adapted to be secured to a part of the machine and having a hat-sided portion, the bracket having a part extending at an angle to said first flange and having a slot extending generally in the direction of the brush, and a screw extending through the bracket slot into a iat side of the stud to secure the bracket in a selected position on said side.

7. A brush holder assembly according to claim 1, in which said bracket has an inclined part extending at an angle to the brush and forming a space between the holder and said inclined part, the inclined part of the bracket being secured against the stud by said releasable device, and the stud having its hat exterior sides located in said space.

References Cited in the le of this patent UNITED STATES PATENTS 522,051 Fuller June 26, 1894 608,135 Lundell July 26, 1898 622,609 Crocket Apr. 4, 1899 922,107 Dunn May 18, 1909 FOREIGN PATENTS 113,686 Great Britain Mar. 7, 1918 226,014 Great Britain Dec. 18, 1924 513,042 Germany Nov. 24, 1930 698,072 Germany Oct. 31, 1940 

